The State Department on Tuesday slapped North Korea with new sanctions over the death of Kim Jong Un's brother, Kim Jong Nam.

On February 22, the United States determined under the Chemical and Biological Weapons Control and Warfare Elimination Act of 1991 that the Government of #NorthKorea used the chemical warfare agent VX to assassinate Kim Jong Nam, in the Kuala Lumpur airport. pic.twitter.com/sxsjeUxTFJ

Kim Jong Nam died last February after two women smeared the banned chemical weapon VX nerve in his face at an airport in Malaysia. The nerve agent is banned under the Chemical and Biological Weapons Control and Welfare Elimination Act of 1991.

"This public display of contempt for universal norms against chemical weapons use further demonstrates the reckless nature of North Korea and underscores that we cannot afford to tolerate a North Korean WMD program of any kind," State Department spokeswoman Heather Nauert said in a statement.

The sanctions were assessed the same day President Donald Trump said there was "possible progress being made in talks with North Korea."

"For the first time in many years, a serious effort is being made by all parties concerned" he tweeted. "The World is watching and waiting! May be false hope, but the U.S. is ready to go hard in either direction!"